The field of dispensing technology has become increasingly important as a result of the incorporation of automatic packaging equipment into modern production facilities. As noted in my earlier patent, U.S. Pat. No. 4,974,755, issued Dec. 4, 1990, particular problems confront the automated dispensing of viscous materials since, due to their relative high surface tension, the materials cling together onto the dispensing equipment to which they are associated. In my patent, I disclose a dispensing valve assembly and system which is relatively simple and durable yet which is highly accurate in dispensing viscous materials. This improved dispensing valve assembly and system incorporated a "snuff-back" feature directed at the elimination of unwanted spillage, drippage and the like.
Viscous materials, as noted in my patent, are flowable but are difficult to handle; examples of these viscous materials which are subject for automated dispensing equipment were given. In the food industry, such materials as butter, peanut butter, jellies, cheeses and the like fit into this category. In the cosmetic industry, viscous materials include such compositions as thick lotions, gels, creams, etc. In the chemical industry, viscous materials are found both in the household chemical industry and the industrial chemical industry. Household chemicals include such diverse products as shoe polish, greases, hand cleaners, etc.; industrial chemicals include greases and other petroleum products, sealants and adhesives, to name a few.
My earlier patent discussed accurate dispensing of these viscous materials, but yet another problem confronts the packaging industry where a manufacturer desires to dispense a composite viscous product that has been blended from a plurality of components. By way of example, in viscous food products a manufacturer may often want to add a flavoring material, a preservative or a coloring agent to a base viscous material in process. In the cosmetics industry, different coloring agents and fragrances may be added to a common base carrier material to produce cosmetics of different hues and shades and products having different olfactory sensations. Likewise, in the chemical industry, coloring agents and other additives may often be incorporated into a composite viscous product. One such example is in the manufacture of caulking compounds wherein a base compound material may be tinted with different colors so that different decorative appearances may be obtained by the user.
Where low viscosity materials are concerned, mixing of a plurality components together so that they are intimately blended often does not present significant problems. On the other hand, viscous materials resist blending by their very nature; hence, either the intimate blending of a plurality of viscous materials together or an additive component to a base viscous material presents a substantial challenge.
Heretofore, manufacturers have found it necessary to blend multi-component viscous systems in large mixing vats thereby requiring a substantial quantity of the material to be prepared as a "minimum run". Where a manufacturer desires to produce a family of products all having a common base material to which is added a different modifying component, such as a coloring agent, it is often necessary for the manufacturer to pre-blend in excessive quantity of each material. This procedure is quite inefficient and generates excessive inventory on one hand and substantial waste on the other.
The reason for these drawbacks is that a manufacturer, after mixing the minimum quantity of the particular member of the family of products, must package the entire quantity of mixed material or otherwise store the blended material for later use. The need to change production and dispensing among the family members necessitates the purging of the dispensing equipment each time a change is made so that substantial waste often results. Further, the need to purge the mixing and dispensing equipment is time consuming and thus expensive to the manufacturer. It is not unusual to use hazardous cleaning compounds to clean mixing equipment and to otherwise purge the dispensing equipment for the various family members when a switch from one family member to another is made. This of course is costly and environmentally unattractive due to hazardous waste disposal problems.
Accordingly, there has been a long felt need for mixing apparatus especially constructed for viscous materials wherein a composite material may be blended from a plurality of components without the need for pre-blending the components prior to their introduction into dispensing apparatus. There has thus been a need for mixing and dispensing apparatus that allows a manufacturer to use a common base material which is altered at the last possible point in the dispensing operation so that only minimal purging and cleaning is required when varying the blended composite material from one type to another. At the same time, there is the need that the blending of plural components is successfully accomplished so that the plural components are intimately mixed with one another.